The device of the present invention relates to a biological indicator for sterilization processes.
In order to test the effectiveness of a steam or gas sterilization process, standardized spores of a bacterial strain sufficiently resistant to the sterilization medium are placed on a carrier, such as a spore disc or strip, and the strip is exposed to the sterilization medium being tested, normally gas, steam or dry heat. A proper sterilization of a standardized spore strain insures sterilization of the bacterial strain in the chamber of the autoclave or other sterilization device. On the other hand, the presence or survival of these standardized spore strains indicates an unsatisfactory sterilization process.
After the sterilization process has been completed, the survival of the spores is determined by mixing a test solution containing a culture or growth medium and a pH indicator with the bacterial spores and thereafter incubating the culture for growth. In spore fermentation, for example, glucose contained in the growth medium is utilized by viable or living spores, and pyruvic acid is produced as a byproduct. The pyruvic acid lowers the pH of the test solution and results in a change of color of the pH indicator in the solution. If there are no living or viable spores following sterilization, the pH and the color of the test solution remains essentially unchanged.
Various ways are known for mixing the test solution with the strips containing the microorganisms or spores. One such way consists of providing a hermetically sealed glass ampule containing the culture medium and enclosing the ampule and the test strip in a container and providing a means to crush the ampule whereby the culture medium floods the test strip in the container. Thereafter, the saturated test strip in the container is incubated for the requisite period of time in order to determine whether or not viable bacteria is present. Devices of the foregoing type are shown, for example, in U.S. Pat. Nos. 3,440,144; 3,661,717 and 4,304,869.
The present invention is an improvement on devices of the foregoing type in that the device of the present invention is relatively inexpensive to fabricate, is reliable in operation, and has other conveniences and features not found in the prior art.